Industrial processes often result in air volumes containing excessive amounts of hydrocarbon molecules such as propane, pentane, or xylene and/or oxygen-carbon-hydrogen containing molecules such as alcohols, aldehydes, ketones and organic acids. Such organic molecules are referred to generically as HC in this text. Certain metal casting processes also result in foundry sand coated with HC-containing residues.
Airborne HC-containing exhaust streams have been subjected to regenerative thermal oxidation (RTO) or regenerative catalytic oxidation (RCO) processes to destroy the unwanted substances. But these thermal processes require fuel and are conducted in special reactors under very high temperature conditions. They require catalyst regeneration (in the case of RCO), and they are expensive for treating HC contaminants in a large volume of air. Furthermore, these thermal processes yield oxides of nitrogen which are considered an environmental problem.
It has also been proposed to use ozone at ambient temperatures for the complete oxidation of HC molecules to carbon dioxide and water. Ozone, O3 the triatomic molecule of oxygen, is a more powerful oxidizing agent than ordinary oxygen. But the susceptibility of the wide range of organic substances in industrial environments to destructive oxidation by ozone varies widely. Ozone has not provided a strong enough tool in treating industrial wastes.
There are manufacturing operations, for example automobile and truck painting operations, from which volumes of HC-containing air are exhausted. In these operations the composition and amount of the HC species varies as does the flow rate of the air stream. There is a need for improved methods, operable at close to ambient temperatures, for the destructive oxidation of unwanted HC substances in air streams. There is a need for such oxidation methods especially where the streams vary in flow rate and HC content. There is a need to provide for more effective use of ozone in the destructive oxidation of hydrogen- and carbon-containing industrial contaminants.